Purpose of Review Peripheral blood mononuclear cells (PBMCs) are used in a wide variety of preclinical assays. Preanalytical variations can have a devastating impact on the results. In this review, we list critical preanalytical factors for PBMC-based assays to develop awareness and orientation to the types of sample preparation and storage that one may consider employing. Recent Findings Critical factors during blood collection are the blood collection tube and anticoagulant, possible stabilizer used, and the pre-isolation blood storage temperature and time. During PBMC isolation, critical factors are the isolation method, density gradient or magnetic sorting, use of barrier, possible RBC lysis, and centrifuge type. During cryopreservation, attention is needed for the cryomedium type and temperature, freezing device and program, cell concentration, and the long-term storage temperature. During the thawing process, the thawing procedure/device used and wash medium temperature are critical. Summary To avoid biased results in PBMC assays, these critical preanalytical factors must be standardized and/or documented. Additionally, participation in external quality assurance programs is strongly recommended.

Biobanks produce and distribute biospecimens, ensuring their fitness for purpose and accurately qualifying them before distribution. In their efforts toward professionalization, biobanks can nowadays seek certification or accreditation. One of the requirements of these standards is regular participation in Proficiency Testing (PT) programs. An international PT program has been developed and provided to biobanks and other laboratories that perform specific tests to qualify different types of biospecimens. This PT program includes biospecimen testing schemes, as well as biospecimen processing interlaboratory exercises. This PT program supports the development of biobank quality assurance by providing the possibility to assess biobank laboratory performance and useful insights into biobank laboratory method performance characteristics and thus fulfill the demands from accreditation authorities.

BackgroundIn this study, we tested to which extent possible between-center differences in standardized operating procedures (SOPs) for biobanking of cerebrospinal fluid (CSF) samples influence the homogeneity of the resulting aliquots and, consequently, the concentrations of the centrally analyzed selected Alzheimer’s disease biomarkers.MethodsProficiency processing samples (PPSs), prepared by pooling of four individual CSF samples, were sent to 10 participating centers, which were asked to perform aliquoting of the PPSs into two secondary aliquots (SAs) under their local SOPs. The resulting SAs were shipped to the central laboratory, where the concentrations of amyloid beta (Aβ) 1–42, pTau181, and albumin were measured in one run with validated routine analytical methods. Total variability of the concentrations, and its within-center and between-center components, were analyzed with hierarchical regression models.ResultsWe observed neglectable variability in the concentrations of pTau181 and albumin across the centers and the aliquots. In contrast, the variability of the Aβ1–42 concentrations was much larger (overall coefficient of variation 31%), with 28% of the between-laboratory component and 10% of the within-laboratory (i.e., between-aliquot) component. We identified duration of the preparation of the aliquots and the centrifugation force as two potential confounders influencing within-center variability and biomarker concentrations, respectively.ConclusionsProficiency processing schemes provide objective evidence for the most critical preanalytical variables. Standardization of these variables may significantly enhance the quality of the collected biospecimens. Studies utilizing retrospective samples collected under different local SOPs need to consider such differences in the statistical evaluations of the data.Electronic supplementary materialThe online version of this article (10.1186/s13195-018-0418-3) contains supplementary material, which is available to authorized users.

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